Responses of maternal and non-maternal ewes to social and mother-young separation.

The response to social deprivation in non-maternal non-pregnant ewes was compared with that in post-parturient ewes kept with their lamb. In addition, the response to separation from the lamb was investigated in lactating ewes at times ranging from 24 h to 2 months post partum. Ewes were observed for 5 min in a 2 × 4 m pen, either in the presence or in the absence of 4 adult conspecifics, after which lactating ewes were deprived of their lamb for a further 5 min. Results indicate that mothers of lambs did not react to isolation from adult conspecifics 24 h after parturition, in contrast to non-lactating females, which showed significant increases in high-pitch bleating, motor activity and eliminative behaviours (p < 0.05 in all cases). On the other hand maternal females reacted very strongly to isolation from their lamb. For some behaviours (high-pitch bleats, nosings) response to separation remained quite high even in mothers of two-month-old lambs. However a clear decrease in responses was noted in most behaviours during the first month, and in some cases during the first week of lactation. Overall these results indicate that there is a dramatic decline in gregariousness during the peripartum period. The comparison of postpartum changes in maternal responses to lamb separation in isolated and grouped ewes suggests a combination of decreased maternal response to separation and recovery of usual social tendencies in the first weeks of lactation. Finally our results also indicate that the nosing of inanimate substrates such as ground and walls generally observed in open-field type tests may be related to social deprivation.